The present invention relates generally to spin-on filters for filtering liquids/fluids, such as motor oil. More specifically the present invention relates to a shut-off valve for a spin-on filter, the shut-off valve being configured so as to restrict the flow of liquid from within the filter when the filter is removed from its base or mounting pad.
While it is acknowledged that various spin-on liquid filters include an anti-drain back valve cooperatively arranged with the inlet port, none of the filters known to the present inventors include any type of shut-off valve associated with the outlet port which valve is completed self-contained within the filter assembly.
There are a variety of valve arrangements for liquid filters which are disclosed in various issued United States patents. The following patent references are believed to provide a representative sampling of these various valve arrangements:
______________________________________ U.S. Pat. No. Patentee Issue Date ______________________________________ 3,388,801 Boyd et al. June 18, 1968 3,589,517 Palmai June 29, 1971 3,608,726 Crowther Sept. 28, 1971 5,030,345 Thomas Jul. 9, 1991 5,049,269 Shah Sept. 17, 1991 ______________________________________
One of the drawbacks with the types of valve designs represented by the listed patents is that portions of the valve extend beyond the outer enclosure wall or end plate of the filter assembly. This type of valve design is not compatible with the requirements for a spin-on filter. Since the shut-off valve of the present invention is fully contained within the filter assembly enclosure, it is compatible with spin-on filters and cooperates with the nature and style of the mounting pad or base to which the spin-on filter assembly is attached. It is a stem portion of the mounting pad which operates to open the valve as the filter assembly is spun onto the mounting pad (threaded engagement). When the filter is spun off of the mounting pad (base) the spring-biased nature of the shut-off valve causes it to close automatically so as to trap any liquid which is retained within the filter. The closed valve prevents any leakage or spillage of the retained liquid until the filter assembly can be disposed of in an environmentally sound and responsible manner.